Estimating the Risk of Vertical Transmission of Dengue: A Prospective Study

The dengue virus, an arbovirus of the Flaviviridae family, infects humans bitten by infected Aedes mosquitoes. This is the most frequent, but not the only, route of transmission1; cases of dengue have been reported after transfusion of blood products,2,3 after accidental blood exposure of health care workers,4 and following mother-to-child transmission.5 The incidence of dengue is increasing worldwide,6,7 and a large proportion of cases are asymptomatic.8 Transmission during pregnancy and fetal outcomes are substantial health issues, but the rate of vertical transmission has not been rigorously described.9 In 2012–2013, a dengue epidemic struck French Guiana with an estimated 13,240 people infected (5.7% of the population). The previous epidemic, in 2010, had affected 4% of the population. The major agent was dengue virus serotype 2 (DENV-2) (95%), although other serotypes cocirculated (DENV-4 < 5%; DENV-1 and DENV-3 < 1% each) indicating that there was a hyperendemic. During the 2012–2013 epidemic, a prospective cohort of pregnant women presenting with dengue infection during pregnancy was set up. It was used to estimate the rate of vertical transmission of dengue, and to describe the clinical and biological characteristics of dengue in pregnant mothers and newborns.